Hi there! I'm a happy Dolphin user on Vista 64 bit.
Revision 3661 x64 used to crash from time to time and I'm absolutely incapable of finding the reason. (Mario Galaxy, for example)

No error message appears. The emulator just hangs and Vista tells me something like "Dolphin doesn't work anymore". It points to some crash logs, but they hardly tell anything, but cryptic numbers.

I updated each and everything, from BIOS to graphic cards driver. I am using a GTX260, Intel Quad Core Q9550, Gigabyte Mainboard... so nothing unusual here.

Out of frustration, I downloaded the x32 version of Dolphin and to this point, it didn't crash (but that doesn't mean much, since x64 doesn't crash regulary: could play 2 days without one crash. Then, without anything different, it crashes every 5 minutes).

My question is: where's the difference between 32 bit and 64 bit versions of Dolphin in a technical way? Is there some improvements over 32 bit? Or is it complete nonsense, because Dolphin never allocates more than 1 GB RAM?

if a program is made for 64bit, then it might be faster.
64bit means that the CPU can "use/calculate" 64bit at a time.
if a program needs to calculate with 64bit then a 64bit computer is faster than 32bit

Considering my 64 bit OS can't even run a x86 version of Dolphin. Doesn't even hurt a bit since 64bit versions are better.
About the occasional crashing, in single core mode (since old revs), i've never experienced random crashes in games that are supposed to run perfectly.